1. Field of the Invention
The present invention relates to a multiband DRC system and a method for controlling the same, and more particularly to a multiband DRC system and a method for controlling the same capable of increasing an overall loudness of an output signal by controlling thresholds and gains of a plurality of DRCs included in the multiband DRC system.
2. Description of the Related Art
A DRC (Dynamic range compressor) dynamically limits and controls an amplitude of an output signal according to that of an input signal.
FIG. 1 is block diagram exemplifying a conventional DRC.
Referring to FIG. 1, the conventional DRC 10 includes a delay line 20, a gain controller 30 and a multiplier 40.
The conventional DRC 10 obtains an amplitude of an input signal in real-time and computes a proper gain, and then adjusts the amplitude of the output signal according to the computed gain.
That is, when the amplitude of the input signal exceeds a predetermined threshold, the gain controller 30 obtains a rate of increase with respect to the threshold, and the multiplier 40 multiplies a reciprocal of the rate to the input signal passed through the delay line 20 to limit the amplitude of the output signal to be below the threshold.
FIG. 2 is a graph exemplifying a relationship between an input level and an output level of the conventional DRC.
As shown on FIG. 2, when the input level exceeds the threshold, the output signal is compressed. That is, when the input level exceeds the threshold, a gain, which is a ratio of the output signal to the input signal, is decreased.
The conventional DRC has following disadvantages.
When the input signal having an amplitude larger than the threshold is concentrated in one frequency band, the amplitude of the output signal is limited according to the amplitude of the input signal. Therefore, it is disadvantageous that the input signal in one frequency band is reproduced with a relatively small loudness. For instance, when an audio signal having an amplitude larger than the threshold is concentrated in a high frequency band, the amplitude of the output signal is limited according to the amplitude the input signal of the high frequency band. Therefore, an audio signal of the low frequency band which has small amplitude than the audio of the high frequency band is reproduced with the relatively small loudness.
Moreover, a speaker with a small diameter has a poor low frequency reproduction capability compared to a speaker with a large diameter. The conventional DRC limits the amplitude of the output signal regardless of the frequency band. Therefore, when the threshold is selected on the basis of the audio signal of the low frequency, the audio signal of the high frequency band can not be sufficiently reproduced.